1. Field of the Invention
The present invention relates to a telescopic cover for use in a machine tool or other industrial machinery.
2. Description of Related Art
A telescopic cover that covers a feed mechanism, such as a feed shaft and a guide face of a machine tool table, to protect it from cutting fluid, chips, etc. is provided with telescopic cover members adapted to expand and contract for protection of the feed mechanism. The cover member however sometimes meanders when it is in motion, and a large impact is caused for example when it stops after a sudden motion.
In a known method to relieve such impact, there are provided telescopic cover members each formed at its distal end with a bellow seal in the form of a wiper. When one of the cover members projects at the maximum from an adjacent cover member, a stopper plate for preventing detachment formed in a rear end of the cover member is in contact with the bellow seal. An impact produced when the cover member projects is thereby relieved (refer to JP 6-11946U).
Also known is a telescopic cover having cover members each provided at a distal end thereof with a wiper clip or the like for removing chips adhered to the telescopic cover (refer to JP2000-308944A and JP2000-308945A).
Further known is a telescopic cover having cover members whose distal ends are each provided with a wiper of a rubber elastic material for preventing intrusion of chips, dusts, oils, or the like for protection of a sliding portion of a machine tool. In order to prevent the increase in friction resistance to the wipers, each wiper is fixed with a hard resin adapted for contact with a sliding face of an adjacent cover member, thus decreasing the friction resistance (refer to JP 3050875Y).
Another cover assembly is known, which includes a stationary cover, a movable cover, and a thin metallic elastic member extending from one cover face for contact with another cover face to seal a gap therebetween, whereby foreign matter adhered to the cover is removed (refer to JP 2-48207Y).
As mentioned above, the telescopic cover is generally so designed that, with a movement of a movable section, a corresponding one or more cover members are moved so that a cover region of the telescopic cover is expanded or contracted as a whole. However, there is a limit in an amount of motion of each cover member, and thus when one of the cover members reaches the stroke limit, it collides with the adjacent cover member to produce an impact. To obviate this, the first-mentioned JP 6-11946U has telescopic cover members each adapted, when projecting, to collide at its rear end with a bellow seal, whereby an impact is relieved. However, when the telescopic cover member retracts into the adjacent one to thereby contract the telescopic cover, these cover members collide with each other. Furthermore, if a gap between adjacent cover members increases due to the wearing away of their sliding parts or the like, the meander of the telescopic cover becomes large. As a result, large noise is produced, and the cover members are liable to be damaged. Although the problem of meandering is lessened in a fixed-end type telescopic cover having both ends respectively fixed to stationary and movable parts, a telescopic cover fixed only at one end is liable to meander, causing a problem.
Technical arts disclosed in the secondly and subsequently mentioned publications are devoted to remove foreign matter adhered to a surface of the telescopic cover or the like, and never contemplate to relieve collision between cover members or prevent the meandering of the telescopic cover.